Ophthalmic surgery requires very delicate and precise incisions, frequently performed under a microscope and dealing with microscopic dimensions. The instrumentation used by the surgeon for this type of operation is extremely specialized and must be precisely exact. The sharpness of the instrument used to make the incisions is critical to the success of the operation.
One prior art device, currently in use, is a disposable microvitreoretinal blade which is essentially an open blade attached to a stem. The blade of this device is exposed at all times and there is a significant risk that the surgeon or other operating room personnel may inadvertently be injured by the extremely sharp, exposed blade. Not only might the surgical personnel be cut by the blade, but it is possible that they could be infected by HIV, hepatitis virus or other pathogens. Wearing surgical gloves will not alleviate this problem because the instrument required during the surgery is sharp enough to puncture surgical gloves very easily. For these reasons, it is advantageous that an ophthalmic lance is used which possesses a sheath to cover the blade and protect the user from injury.
In U.S. Pat. No. 4,414,974 Dotson et al. presented a one-time-use microsurgical knife with a slidable shroud that can be moved into a forward, sheathed position to protect the blade, and can be moved back to allow use of the knife. The shroud 18 of Dotson et al.'s invention slides down the cylindrical member 11 to cover the smaller forward tip 14 and the cutting blade 15. To then expose the blade 15, the user must slide the shroud 18 back up the cylindrical member 11.
In U.S. Pat. No. 4,360,016 Sarrine presented a blood collecting device which includes a lancet blade 40 which is exposed and locked in an extended position by pressing the button 48. To retract the lancet blade 40, the finger 50 is pressed causing the lancet blade 40 to retract within the outer surface 17 of the collar 16.
In U.S. Pat. No. 4,491,132 Aikins presented a sheath and retractable surgical tool combination to be used in closed surgical procedures, such as arthroscopy. The protective sheath 10 allows the scalpel blade 30 to be inserted into the actual operative site of the body, minimizing the accidental cutting of surrounding tissue. To then expose the blade 30, the sheath 10 is slid up the blade handle 40 until the pin 26 engages a hole 58 at the desired position. The blade 30 can be exposed at a plurality of positions from partial exposure to full exposure of the blade 30.
In U.S. Pat. No. 4,733,662 DeSatnick et al. presented a tissue gripping and cutting assembly for surgical instruments which includes a reusable handle and a removable sheathed blade assembly. The blade assembly 24 is exposed or retracted by an internal slider 26 controlled by a single finger manipulable external slide button 28.
In U.S. Pat. No. 5,071,426 Dolgin et al. presented a surgical scalpel with retractable blade guard which is mounted for movement between a blade-guarded position and a blade exposed position. Depressing the actuating arm 18 towards the body 12 will cause the blade guard 16 to slide backwards to expose the blade 14. To release the guard and again cover the blade, the surgeon must again apply pressure to the actuating arm 18.
None of these references in the prior art present a surgical instrument with a blade that is automatically retractable and is only exposed while the user is pressing a button. What is needed for the safety of patients, surgeons and medical staff, is a surgical instrument that includes a blade which is automatically retractable and is only exposed while the user is pressing a button, and the surgical instrument also including a locking position which will not allow the blade to be exposed even when the button is pressed.